Irish language, also called Irish Gaelic and Erse, member of the Goidelic group of the Celtic subfamily of the Indo-European family of languages (see Celtic languages). The history of Irish as a literary language falls into three periods: Old Irish (7th–9th cent. AD), Middle Irish (10th–16th cent.), and Modern Irish (since the 16th cent.). In the medieval period a great Irish literature flourished. Grammatically, there are still four cases for the noun (nominative, genitive, vocative, and, in some dialects, dative). In pronunciation the stress is on the first syllable. An acute accent is placed over a vowel to denote length, and a dot is placed over a consonant to indicate aspiration. The alphabet employed today for Irish can be called a variant or a derivative of the Roman alphabet that took shape about the 8th cent. AD It has 18 letters: 13 consonants and 5 vowels. The oldest extant Irish texts are inscriptions written in the ogham script (see ogham). These texts date back to the 5th cent. AD or perhaps earlier and differ as much from the early literary Irish that follows them as Latin does from Old French. Native speakers of Irish are now concentrated in the western counties of Ireland. The government of Ireland is trying, thus far unsuccessfully, to revive Irish as the primary language of the country; it is an official language, and the study of Irish is required in preparatory schools. See also Gaelic literature.

See H. Wagner, Linguistic Atlas and Survey of Irish Dialects (4 vol., 1958–69); R. P. M. and W. P. Lehman, An Introduction to Old Irish (1975).